Degree

Degree is a measure of an angle. It is the 360th part of a complete rotation, and is therefore the 90th part of a right angle. It is subdivided into 60 minutes, and each minute into 60 seconds; in chartography and navigation, the 1/360th part either of any circumference of the earth which passes through the poles, or of any circle drawn about the earth parallel with the equator. The circumference of the earth through the poles being constant, any 1/360th part of that circumference is, of course, the same in length as any other. The degree of latitude, in consequence, does not vary in length, and measures a little less than 60 geographical miles, or admiralty knots of 6,080 feet each. The degree of longitude, on the other hand, varies in length at every latitude north or south. At 0° latitude, i.e. at the equator, a degree measures exactly 60 nautical or geographical miles, that is, 69.173 statute miles. At intervals of 10 degrees of latitude the length of a degree of longitude, in miles, is as follows: -

Latitude - Miles
0° - - - - 69.07
10° - - - 67.95
20° - - - 64.84
30° - - - 59.75
40° - - - 52.85
50° - - - 44.35
60° - - - 34.50
70° - - - 23.60
80° - - - 11.98
90° - - - 0